The invention relates to a dosing pump device for dosing metered amounts of a liquid product to a beverage machine. More in particular the invention relates to a dosing pump that does neither need to be self-priming, nor requires any purging of air or gasses to effect priming.
It is generally known for pumps to be self-priming, or to be purged prior to a pumping operation. When pumps are used for metering accurate amount, especially in the preparation of beverages that are suitable for human consumption, pump priming becomes very critical. Accuracy and reproducibility of the dosing of ingredients can easily become compromised by air pockets existing in a pump housing, or by delays in the delivery of fluids from the pump. The smaller the amount to be dosed per cycle, the more serious any deviations from proper metering will work out in a beverage resulting from that cycle.